Medical monitors for gathering and displaying medical information concerning the physiological status of a patient are well known. Examples of the physiological status monitored by such devices include a patient's heart rate, electrocardiogram (EKG), breathing rate, etc. Many medical monitors include a display for providing immediate information to a user. However, information displayed to the user is not retained after it is displayed for use by other medical personnel. Some medical monitors are capable of being used in combination with a printer to print the medical information so that it can be kept and referred to by other medical personnel.
Conventional medical monitors that are capable of being used in combination with printers use strip chart recorders that have thermal array printing heads. Strip chart recorders are preferred since they are most convenient for recording the elongate graph-like information typically provided by medical monitors. Thermal array printing heads are preferred since they are quiet providing comfort to the patient being monitored as well as neighboring patients. Further, thermal array printing heads provide substantially laser quality printing without the delay that is typical of laser printers.
Strip chart recorders that are in common use with medical monitors are constructed to print the medical information in various formats that differ by the width of the paper that the strip chart recorder is constructed to accommodate. Common sizes for strip chart recorder paper is approximately two inches in width and approximately four inches in width. Although strip chart recorders can be manufactured to accommodate either of the foregoing paper sizes, or any other of a wide range of paper sizes, strip chart recorders typically available are not capable of printing on paper of various sizes. In other words, once manufactured, a particular strip chart recorder is capable of being used with only one size paper.
These strip chart recorders, and medical monitors that are constructed for use in combination with these strip chart recorders, are not desirable since they limit the ability of the user to select the appropriate paper size for the specific monitoring task. As an example, strip chart recorders that are constructed for use with paper of a relatively small width preserve the paper that is used and, since the paper used with thermal array printing heads is expensive, save cost. However, these strip chart recorders are disadvantageous for tasks that require more information be printed than what can be positioned on the relatively small width paper. As another example, strip chart recorders that are constructed for use with paper of a relatively large width allow for more information to be printed but provide a substantial waste of paper for tasks that require less information to be printed. Accordingly, it is desirable to provide a medical monitor that is capable of printing information on paper of various sizes.
Some medical monitors have been manufactured that can be used with various strip chart recorders so that different strip chart recorders can be selected to vary the size of paper to be printed upon. These medical monitors are not desirable since they typically require that the medical monitor be reconfigured when the strip chart recorder is changed so that the medical information is properly formatted for the paper width that is being used. The user will often print little information when a patient's condition is relatively stable, but should the patient's condition change, then it is necessary to rapidly begin to print more medical information. However, using the above-described strip chart recorders valuable time is wasted while reconfiguring the medical monitor, time that medical information could be recorded and that the user could be attending to other, more important tasks. Accordingly, it is desirable to provide a medical monitor that is capable of printing on paper of various widths and of rapidly changing from one paper width to another.